70 



SYSTEMATIC ARRANGEMENT 



Fam. III. CYVKJEADM. 



Shell ventricose, involute. Mouth linear ; lips toothed. Canal 

 recurved like a notch. Rostrum short. Tentacles elongate, subu- 

 late. Eyes external, basal. Mantle expanded on the sides. Gill 

 with a siphon at each end, in a single series. Lateral teeth on 

 tongue-membrane conical, curved. Shell of young smooth. Oper- 

 culum none. 



The individuals of the same species vary greatly in size, in the 

 thickness of the base and margin, in the general form, and rarely in 

 the size of the teeth ; their most constant characters are the form of 

 the front of the columella, the number of the teeth, and the general 

 distribution of the colour. The great difference in size of the 

 adults of the same species has been attempted to be explained by the 

 theory that the animals shed their shells as the lobsters do their 

 skin ; but this is not the case ; young shells may be found of all the 

 various sizes. Individuals are to be found of most of the species 

 which have had a coat of enamel (generally similar in colour to the 

 margin) which has been deposited on their backs, after they have 

 arrived at their full colour ; sometimes this coat is blistery. 



The young specimens, before the mouth of the shell is formed, 

 have the mantle on the pillar side dilated and bearded, and of the 

 outer side simple, with a slightly thickened edge. The foot is trun- 

 cated. The tentacles subulate, far apart on each side of the trunk ; 

 eyes on small tubercles at the outside of the base of the tentacles. 

 Foot simple, folded longitudinally when contracted ; the lobes of the 

 mantle often covered with tentacles. 



The young shells (fig. 39) greatly 

 resemble the shell of Bullina in general 

 form, but they are distinguished from 

 it by the inner lip not being thickened 

 or elevated. The young shell of most 

 of the species is smooth, but the young 

 of Cyprcea pustulata is covered with 

 regular, spiral, rather flat-tipped con- 

 centric ridges, with equal wide grooves 

 between them ; and the nucleus of Cy- 

 prcea nigropunctata, which is only to 

 be seen in the young shell, is finely, 

 concentrically and spirally ridged, so as 

 to be closely and acutely cancellated. 

 The young shells under some particular 

 circumstances have a ridge round the 

 inner part of the outer lip, which is 

 sharp, compressed, and strongly denticulated in front. These shells 

 appear to have belonged to an animal which for some reason was 

 prevented from forming a proper mouth to the shell. 



The animal of C. arabica is black-brown, with a yellow edge to 



Fig. 39. — Cyprcea testudinaria. 

 Young shell. 



